java - Exception in thread "main" adding window to container -

i writing app select random numbers click on jbutton. when run app exception:

exception in thread "main" java.lang.illegalargumentexception: adding window container @ java.awt.container.checknotawindow(container.java:483) @ java.awt.container.addimpl(container.java:1084) @ java.awt.container.add(container.java:410) @ final.main(final.java:37)

here code:

import java.util.arraylist; import java.awt.*; import javax.swing.*; import java.awt.event.actionevent; import java.awt.event.actionlistener;   public class final extends jpanel {      public static void main(string[] args) {          // random numbers have selected         arraylist numbers = new arraylist();         numbers.add(40);         numbers.add(500);         numbers.add(90);         numbers.add(10);         numbers.add(50);         numbers.add(25);          // panel gui         jpanel panel = new jpanel();         // , of course frame , characteristics         jframe frame = new jframe();         frame.setdefaultcloseoperation(jframe.exit_on_close);         frame.settitle("random numbers!");         frame.setvisible(true);         frame.setsize(300,150);           // button selecting random number arraylist         jbutton button = new jbutton();         button.settext("click me!");          // add objects panel         frame.add(button);         panel.add(frame);             }  } 

instead of:

    // add objects panel     frame.add(button);     panel.add(frame);         

try like:

    // add objects panel     frame.add(button, borderlayout.page_start); // top of frame     frame.add(panel); // defaults center